Answer:
THE VOLUME OF NaOH NEEDED TO BE ADDED TO CITRIC ACID TO REACH THE EQUIVALENT POINT IS 4.725 L
Explanation:
The titration is between citric acid (H3C6H507) and NaOH
mass of citric acid = 0.306 g
Volume of citric acid = 250 mL = 250 /1000 = 0.25 L
Concentration of NaOH = 0.1000 M
Volume = unknown
First calculate the molar mass of citric acid
( 1 * 3 + 12* 6 + 1*5 + 16*7) = (4 + 72 + 5 + 112) = 193 g/mol
Since,
Concentration in moles/dm3 = concentration in g/dm3 / RMM
So the molarity of citric acid is:
Molarity = 0.306g / 0.25dm3 / Rmm
Molarity = 1.224g/dm3 / 193 g/mol
Molarity = 0.0063 M
Equation for the reaction is:
C3H5O(COOH)3 + 3NaOH → Na3C3H5O(COO)3 + 3H2O
Using the formula:
CaVa / CbVb = na/ nb
Ca = 0.0063 M
Cb = 0.1000 M
Va = 0.25 L
Vb = unknown
na = 1
nb = 3
Vb = Ca Va nb/ Cb na
Vb = 0.0063 * 0.25 * 3 / 0.1000 * 1
Vb = 0.4725 / 0.1000
Vb = 4.725 L
The volume of NaOH needed to reach the equivalent point is therefore 4.725 L
What is in period 6 group 8
Answer:
Osmium
Explanation:
If you take a look at the attached image of a periodic table below, you will see that the element in the 6th period and 8th group is Osmium. Hope this helps!
1. Which statement describes the particles of an ideal gas, based on the
kinetic molecular theory?*
O There are attractive forces between the particles.
O The particles move in circular paths.
O The collisions between the particles reduce the total energy of the gas.
О
The volume of the gas particles is negligible compared with the total volume of the
gas.
Answer:the volume of the gas particles is negligible compared with the total volume of the gas.--D
Explanation:
According to the Kinetic Molecular Theory for ideal gases, it states that
--Gases are composed of larges molecules which are in constant random motion in a straight line
--The volume of the gas particles is negligible compared to the total volume in which the gas is contained.
-----The Attractive and repulsive forces between gas molecules is insignificant ie There are no interactive forces.
----The collisions of the particles are perfectly elastic and energyis being transferred between the particles but the total energy remaining constant
From the statements of the kinetic Molecular theory of ideal gases, it can be seen that the statement which describes the particles of an ideal gas is option D which is The volume of the gas particles is negligible compared with the total volume of the gas--- ---This gives the reason why gases can be compressed. Since there are no inter molecular forces between them. The particles of an ideal gas will move at the same random motion resulting to high pressures, compressing the gas and making the volume negligible or insignificant.
when a car drives down a street, what evergy conversions are happening?
Compare the conjugate bases of these three acids. Acid 1: hypochlorous acid , HClO Acid 2: phosphoric acid , H3PO4 Acid 3: hydrogen sulfide , HS- What is the formula for the weakest conjugate base ?
Answer:
The weakest conjugate is HClO-.
Explanation:
As a general rule, the stronger the Bronsted-Lowry acid, the weaker its conjugate base, and vice versa.
Acid 1: HClO is a strong acid, hence its conjugate base would be weak
Acid 2: H3PO4 is a weak acid, hence its conjugate base would be strong
Acid 3: hydrogen sulphide is also a moderately weak acid with a moderately strong conjugate base.
In order of increasing strengths:
HClO < H2S < H3PO4
The decay of a radioactive material is monitored using a Geiger counter. At the start, the count rate is 2000 decays/minute. Four hours later the decay rate is 500 counts/min. What is the half-life of the material?
Answer:
The half-life of the material is 2 years
Explanation:
Given;
initial count rate = 2000 decays/minute
final count rate = 500 counts/min
decay time = Four hours
To determine the half life of the material; we create a simple decay table that matches the decay time and count rates.
time (years) count rate
0 2000 decays/minute
2 1000 decays/minute
4 500 decays/minute
Half life is the time intervals = 2 years
Also using a formula;
[tex]N = \frac{N_o}{(t/2)^2} \\\\N_o-is \ the \ initial \ count\ rate\\\\N-is \ the \ final \ count\ rate\\\\t/_2 - is \ the\ half\ life \\\\N = \frac{N_o}{(t/2)^2} \\\\500 = \frac{2000}{(t/2)^2}\\\\(t/_2)^2 = \frac{2000}{500} \\\\(t/_2)^2 = 4\\\\t/_2 = \sqrt{4} \\\\t/_2 = 2 \ years[/tex]
Therefore, the half-life of the material is 2 years
Given a K value of 0.43 for the following aqueous equilibrium, suppose sample Z is placed into water such that it’s original concentration is 0.033 M. Assume there was zero initial concentration of either A(aq) or B(aq). Once equilibrium has occurred, what will be the equilibrium concentration of Z?
2A(aq) + B(aq) <> 2Z (aq)
Answer:
[Z] = 0.00248M
Explanation:
Based in the reaction:
2A(aq) + B(aq) ⇄ 2Z (aq)
K of the reaction is defined as:
K = [Z]² / [A]²[B] = 0.43
If you add, in the first, just 0.033M of Z, concentrations in equilibrium are:
[Z] = 0.033M - 2X
[A] = 2X
[B] = X
Replacing in K equation:
0.43 = [0.033M - 2X]² / [2X]² [X]
0.43 = [0.033M - 2X]² / [2X]² [X]
0.43 = 4X² -0.132X + 0.001089 / 4X³
1.72X³ - 4X² + 0.132X - 0.001089 = 0
Solving for X:
X = 0.01526M
Replacing, concentration in equilibrium of Z is:
[Z] = 0.033M - 2*0.01526M = 0.00248M
Answer:
Less than 0.033 M
Explanation:
Hello,
In this case, given the equilibrium:
[tex]2A(aq) + B(aq) \rightleftharpoons 2Z (aq)[/tex]
Thus, the law of mass action is:
[tex]K=\frac{[Z]^2}{[A]^2[B]}[/tex]
Nevertheless, given the initial concentration of Z that is 0.033 M, we should invert the equilibrium since the reaction will move leftwards:
[tex]\frac{1}{K} =\frac{[A]^2[B]}{[Z]^2}=2.33[/tex]
Know, by introducing the change due to the reaction extent, we can write:
[tex]2.33=\frac{(2x)^2*x}{(0.033M-2x)^2}[/tex]
Which has the following solution:
[tex]x_1=2.29M\\x_2=0.0181M\\x_3= 0.0153M[/tex]
But the correct solution is [tex]x=0.0153M[/tex] since the other solutions make the equilibrium concentration of Z negative which is not possible. In such a way, its concentration at equilibrium is:
[tex][Z]_{eq}=0.033M-2*0.0153M=0.0024M[/tex]
Which is of course less than 0.033 M since the addition of a product shift the reaction leftwards in order to reestablish equilibrium (Le Chatelier's principle).
Regards.
At 25 °C, what is the hydroxide ion concentration, [OH−] , in an aqueous solution with a hydrogen ion concentration of [H+]=1.9×10−9 M?
Answer:
The correct answer will be "5.26 × 10⁻⁶".
Explanation:
The given values is:
[tex][H^{+}]=1.9\times 10^{-9} M[/tex]
As we know,
⇒ [tex]pH+pOH=14[/tex]
On taking log, we get
⇒ [tex]-log[H^{+}] + -log[OH^{-}] = 14[/tex]
Now,
Taking "log" as common, we get
⇒ [tex]log[H^{+}][OH^{-}]= -14[/tex]
⇒ [tex][H^{+}][OH^{-}]= 10^{-14}[/tex]
⇒ [tex][OH^{-}]=\frac{10^{-14}}{[H^{+}]}[/tex]
On putting the estimated value of "[tex][H^{+}][/tex]", we get
⇒ [tex]=\frac{10^{-14}}{1.9\times 10^{-9}}[/tex]
⇒ [tex]=5.26\times 10^{-6}[/tex]
A blood sample is left on a phlebotomy tray for 4 hours before it is delivered to the laboratory. Which group of tests could be performed:
A 25.0 mL solution of quinine was titrated with 1.00 M hydrochloric acid, HCl. It was found that the solution contained 0.125 moles of quinine. What was the pH of the solution after 50.00 mL of the HCl solution were added
Answer:
pH = 9.08
Explanation:
Quinine, C₂₀H₂₄O₂N₂, Q, is a weak base that, in water, has as equilibrium:
Q + H₂O ⇄ QH⁺ + OH⁻
Where pKb is 5.10
Using H-H equation for weak bases:
pOH = pKb + log₁₀ [QH⁺] / [Q]
The reaction of quinine with HCl is:
Q + HCl → QH⁺ + Cl⁻
Initial moles of quinine are 0.125 moles and moles added of HCl are:
0.05000L × (1.00mol / L) = 0.05000moles.
That means after the addition of 50.00mL of the HCl solution, moles of Q and QH⁺ are:
Q = 0.125mol - 0.050mol = 0.075 moles
QH⁺ = 0.050 moles
Replacing in H-H equation:
pOH = 5.10 + log₁₀ [0.050] / [0.075]
pOH = 4.92
As pH = 14 - pOJ
pH = 9.08What is the Arrhenius definition of an acid? A substance that increases H3O+ concentration when it is dissolved in water. A substance that increases OH– concentration when it is dissolved in water. A compound that donates protons. A compound that accepts protons.
Answer:
A substance that increases H3O+ concentration when it is dissolved in water.
Explanation:
Note that H3O+ and H+ are used quite interchangeably in chemistry.
An acid makes the H+ content higher, thereby decreasing the pH.
Answer:
a
A substance that increases H3O+ concentration when it is dissolved in water.
Explanation:
RUIGA GIRLS
CHEMISTRY FORM 3. 23/06/2020
MR. GICHURU
IZ
1
Narne the elements present in
Common salt
(2 miks)
Hydrated copper (11) Sulphate.
(2 ks)
Sulphuric (VI) acid,
2 Why is a reaction between zinc metal and Nitric acid not suitable for preparing
hydrogen gae in the laboratory
(2 mi)
(1 m)
3.
What is relative atomic mass?
b)
Define 'isotopes
c)Determine the relative atomic mass of element K whose isotople misure occur in
the proportione:
(2 marks)
A compound has an empirical formula of CHN. What is the molecular formula, if it’s molar mass is 135.13 g/mol? (C=12.01 amu, H=1.008 amu, N= 14.01)
Answer:
well the MF is 224.78 g/mol
Explanation:
just times them all by the molor mass and divide it by 3
Explain, in terms of charge distribution, why a molecule of carbon tetrachloride is a nonpolar molecule.
Answer:
Explanation:
The covalent bond is the chemical bond between atoms where electrons are shared, forming a molecule. Covalent bonds are established between non-metallic elements, such as hydrogen H, oxygen O and chlorine Cl. These elements have many electrons in their outermost level (valence electrons) and have a tendency to gain electrons to acquire the stability of the electronic structure of noble gas.
The covalent bond between two atoms can be polar or nonpolar. If the atoms are equal, the bond will be nonpolar (since no atom attracts electrons more strongly). But, if the atoms are different, the bond will be polarized towards the most electronegative atom, because it will be the atom that attracts the electron pair with more force. Then it will be polar.
It can occur in a molecule that the bonds are polar and the molecule is nonpolar. This occurs because of the geometry of the molecule, which causes them to cancel the different equal polar bonds of the molecule.
In carbon tetrachloride the bonds are polar, but the tetrahedral geometry of the molecule causes all four dipoles to cancel out and the molecule to be apolar.
The carbon tetrachloride s CCL4 is a carbon molecule and four chloride molecule's. The carbon tetrachloride is a nonpolar, as the dipole movement of the molecules ae evenly spaced around the central carbon atom.
As polarity is a result of the geometric sum of the bond dipoles. The bond has separate charges. It's nonpolar because the charge is symmetrically distributed.Hence the carbon tetrachloride happens to be a nonpolar molecular.
Learn more about the in terms of charge distribution, why a molecule.
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A sample of 6.022 x 1023 particles of gas has a volume of 22.4 L at 0°C and a pressure of 1.000 atm. Although it may seem silly to contemplate, what volume would 1 particle of gas occupy?
pv=nRT
Answer:
1 particle of the gas would occupy a volume of 3.718*10⁻²³L
Explanation:
Hello,
1. The sample has a particle of 6.022×10²²particles
2. Volume of the sample = 22.4L
3. Temperature of the sample = 0°C = (0 +273.15)K = 273.15K
4. Pressure of the sample = 1.0atm
What volume would 1 particle of the gas occupy?
But we remember that 1 mole of any substance = 6.022×10²² molecules or particles or atoms
What would be the number of moles for 1 particule?
1 mole = 6.022×10²² particles
X moles = 1 particle
X = (1 × 1) / 6.022×10²² particles
X = 1.66×10⁻²⁴ moles
Therefore, 1 particle contains 1.66×10⁻²⁴ moles
Since we know our number of moles, we can proceed to use ideal gas equation,
Ideal gas equation holds for all ideal gas and is defined as
PV = nRT
P = pressure of the ideal gas
V = volume the gas occupies
n = number of moles of the gas
R = ideal gas constant = 0.082 L.atm / mol.K
T = temperature of the gas
PV = nRT
Solving for V,
V = nRT/ P
We can now plug in our values into the above
equation.
V = (1.66*10⁻²⁴ × 0.082 × 273.15) / 1
V = 3.718*10⁻²³L
Therefore, 1 particule of the gas would occupy a volume of 3.718*10⁻²³L.
The reaction of hydrogen and iodine to produce hydrogen iodide has a Kc of 54.3 at 703 K. Given the initial concentrations of H2 and I2 are 0.453 M, what will the concentration of HI be at equilibrium
Answer:
[HI] = 0.7126 M
Explanation:
Step 1: Data given
Kc = 54.3
Temperature = 703 K
Initial concentration of H2 and I2 = 0.453 M
Step 2: the balanced equation
H2 + I2 ⇆ 2HI
Step 3: The initial concentration
[H2] = 0.453 M
[I2] = 0.453 M
[HI] = 0 M
Step 4: The concentration at equilibrium
[H2] = 0.453 - X
[I2] = 0.453 - X
[HI] = 2X
Step 5: Calculate Kc
Kc = [Hi]² / [H2][I2]
54.3 = 4x² / (0.453 - X(0.453-X)
X = 0.3563
[H2] = 0.453 - 0.3563 = 0.0967 M
[I2] = 0.453 - 0.3563 = 0.0967 M
[HI] = 2X = 2*0.3563 = 0.7126 M
Is chemical engineering suits for a person who gets bored fast and needed to learn new things?
Answer:
yes
Explanation:
because it will keep them entertained and will learn new things
The solubility of cadmium oxalate, , in 0.150 M ammonia is mol/L. What is the oxalate ion concentration in the saturated solution? If the solubility product constant for cadmium oxalate is , what must be the cadmium ion concentration in the solution? Now, calculate the formation constant for the complex ion
Answer:
[Cd²⁺] = 2.459x10⁻⁶M
Kf = 9.96x10⁶
Explanation:
Solubility of CdC₂O₄ is 6.1x10⁻³M and ksp is 1.5x10⁻⁸
The ksp of CdC₂O₄ is:
CdC₂O₄(s) ⇄ Cd²⁺(aq) + C₂O₄²⁻(aq)
ksp = [Cd²⁺] [C₂O₄²⁻] = 1.5x10⁻⁸
As solubility is 6.1x10⁻³M, concentration of C₂O₄²⁻ ions is 6.1x10⁻³M. Replacing:
[Cd²⁺] = 1.5x10⁻⁸ / [6.1x10⁻³M]
[Cd²⁺] = 2.459x10⁻⁶MAll Cd²⁺ in solution is 6.1x10⁻³M and exist as Cd²⁺ and as Cd(NH₃)₄²⁺. That means concentration of Cd(NH₃)₄²⁺ is:
[Cd(NH₃)₄²⁺] + [Cd²⁺] = 6.1x10⁻³M
[Cd(NH₃)₄²⁺] = 6.1x10⁻³M - 2.459x10⁻⁶M = 6.098x10⁻³M
[Cd(NH₃)₄²⁺] = 6.098x10⁻³MIn the same way, the whole concentration of NH₃ in solution is 0.150M, as you have 4ₓ6.098x10⁻³M = 0.024M of NH₃ producing the complex, the concentration of the free NH₃ is:
[0.150M] = [NH₃] + 0.024M
0.1256M = [NH₃]The equilibrium of the complex formation is:
Cd²⁺ + 4 NH₃ → Cd(NH₃)₄²⁺
The kf, formation constant, is defined as:
Kf = [Cd(NH₃)₄²⁺] / [Cd²⁺] [NH₃]⁴
Replacing:
Kf = [6.098x10⁻³M] / [2.459x10⁻⁶M] [0.1256M]⁴
Kf = 9.96x10⁶what is the name of the liquid in the clinical thermometer
Answer:I suppose it is mercury...
Explanation:
I don't say u must have to mark my ans as brainliest but if it has really helped u plz don't forget to thnk me...
How is the mass of the atom calculated?
by adding the number of protons and electrons
by adding the number of protons and neutrons
by subtracting the number of electrons from the number of protons
by adding the number of neutrons and electrons
The mass of the atom is calculated by adding the number of protons and neutrons .
What do you mean by atomic mass of an element ?The total mass of one atom of an element is defined as its atomic mass. The atomic mass is taken as the mass of protons and neutrons in an atom.
1 a m u = 1.66 ×10⁻²⁴g
To calculate the atomic mass of an element -:
The atomic mass of the single atom can be calculated by adding the total number of protons and the total number of neutrons of that particular atom.
Atomic mass Number = Number of protons + number of neutrons
Hence ,in this way the atomic mass is calculated of an atom .
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How many moles of H2 are needed to produce 34.8 moles of NH3?
2 i hope this helps
:)✨✨✨✨✨✨
1. ______The force that keeps the nucleons bound inside the nucleus of an atom
A. Strong electrostatic force
B. Strong nuclear force
C. Strong centripetal force
D. Gravitational attraction
2._____The amount of energy needed to split the nucleus into individual protons and neutrons
A. Nuclide transfer energy
B. Nuclear binding energy
C. Mass energy equivalence
D. Nuclear energy
3._______ The difference between the mass of the nucleons and the mass of an Atom
A. Mass of nucleus
B. Mass defect
C. Atomic mass
D. Isotopic mass
Answer:
1). strong nuclear force 2). nuclear binding energy 3), mass defect
Explanation:
Right on Edge
1. Strong nuclear force the force that keeps the nucleons bound inside the nucleus of an atom.
2. Nuclear binding energy the amount of energy needed to split the nucleus into individual protons and neutrons.
3. Mass defect the difference between the mass of the nucleons and the mass of an Atom.
What is strong nuclear force ?The term strong nuclear force is defined as the force that binds protons and neutrons together. It also binds them all together in a nucleus and is responsible for the energy released in nuclear reactions.
The examples of strong nuclear force are the force that hold protons and neutrons in nuclei of atoms. The elements' greater than the hydrogen atom. The fusion of hydrogen into helium in the sun's core.
Thus, 1. option B, 2. option B and 3. option B is correct.
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Monel metal is a corrosion-resistant copper-nickel alloy used in the electronics industry. A particular alloy with a density of 8.80 g/cm3 and containing 0.090 % Si by mass is used to make a rectangular plate that is 15.0 cm long, 12.5 cm wide, and 3.50 mm thick and has a 2.50-cm-diameter hole drilled through its center such that the height of the hole is 3.50 mm .
The silicon in the plate is a mixture of naturally occurring isotopes. One of the those isotopes is silicon-30, which has an atomic mass of 29.97376 amu. The percent natural abundance, which refers to the atoms of a specific isotope, of silicon-30 is 3.10%.
Part A What is the volume of the plate?Express the volume numerically in cubic centimeters.
Part B How many silicon-30 atoms are found in this plate?
Express your answer numerically using two significant figures.
Answer:
Based on the given question, the dimensions of the plate is 15 cm in length, 12.5 cm in width, and 3.50 mm in thickness (0.350 cm). Now the volume of the plate will be,
V = 15 cm × 12.5 cm × 0.350 cm = 65.62 cm³
A hole of diameter 2.50 cm is drilled through the center of the plate, at the height of 3.50 mm or 0.350 cm. Now the volume of the hole is π(r)²h,
= 22/7 × (1.25 cm)² × 0.350 cm = 1.72 cm³
Thus, the volume of the plate will be determined by subtracting the volume of plate with the volume of hole, which will be,
65.62 cm³ - 1.72 cm³ = 63.9 cm³
The density of the alloy is 8.80 g/cm³, therefore, the mass of the alloy can be determined by using the formula, mass = density * volume
mass = 8.80 g/cm³ × 63.9 cm³ = 562.32 grams
Of the total alloy, 0.090 percent is Si, that is,
(0.090/100) × 562.32 g = 0.506 grams of Si
The natural abundance of the element is not determined by mass but by the number of atoms it possess. For this Avogadro's number and atomic mass of Si is used. Now the number of atoms of Si present is,
(0.506 g) (1 mol/28.0855 g) (6.023 × 10²³ atoms /mol) = 1.08 × 10²² Si atoms
Of these Si atoms, 3.10 percent are Si-30 so,
= (3.10 / 100) × (1.08 × 10²² atoms) / 1000 = 3.34 × 10²⁰ atoms of Si-30. or 3.4 × 10²⁰ atoms
what happens when you combine Mg2 and NO3
Answer: they blow up
Explanation: add them together and they will blow up
Answer:
Magnesium nitrate Reactions
Magnesium nitrate has a high affinity towards water. Therefore, heating it results to decompose into magnesium oxide, nitrogen oxides, and oxygen. 2 Mg(NO3)2 → 2 MgO + 4 NO2 + O2.
In Chapter 4, we will learn that single bonds experience free rotation at room temperature, while double bonds do not. Consider the two C-N bonds in the structure. One of these bonds exhibits free rotation, as expected for a single bond, but the other C-N bond exhibits restricted rotation. Identify the C-N bond with restricted rotation, and justify your answer by drawing resonance structures.
Answer:
Explanation:
The main objective here is to draw a diagram of an heterocyclic compound containing two C-N bonds in the structure. One with free rotation, as expected for a single bond, but the other C-N bond exhibits restricted rotation. After that ; we will identify the C-N bond with restricted rotation, and also justify our answer by drawing resonance structures.
So; the first image below shows the structure of the heterocyclic compound containing two C-N bonds in the structure with One with free rotation, as expected for a single bond, but the other C-N bond exhibits restricted rotation. From the first diagram. the squared area indicates the C-N bond that exhibits restricted rotation.
The amide bonds in the C-N bonds offers the resonance characteristics and thus exhibits restricted rotation. The resonance is shown in the second image below
Suppose that a wave has a period of 0.03 seconds what is its frequency be sure to show the steps for your work
Answer:
f = 33.34 Hz
Explanation:
A wave has a period of 0.03 seconds. It is required to find the frequency of a wave. The relation between time period and frequency is inverse. The time period of a wave is given by :
T = 1/f, f = frequency of wave
[tex]f=\dfrac{1}{T}\\\\f=\dfrac{1}{0.03}\\\\f=33.34\ Hz[/tex]
So, the frequency of the wave is 33.34 Hz.
Given the equation:
н
H
H
H
H H H H H H
1
H H
7
C=C
/
H H
+
+
C=C
...
... -
C=C
/
Н.
с C-C-...
|
TI
H H H H H H
I-O-I
I-O-I
1
Н
H
н
Which type of reaction is represented by this equation?
1.
combustion
2.
esterification
3.
polymerization
4
substitution
Submit Answer
Answer:
The type of reaction is Polymerization
Answer:
combustion?
Explanation:
Yo, like what is that question.
tertbutylamine and ammonia. Which is more basic
Answer:
ammonia
Explanation:
Glycine, C2H5O2N, is important for biological energy. The combustion reaction of glycine is given by the equation 4C2H5O2N(s) + 9O2(g) → 8CO2(g) + 10H2O(l) + 2N2(g) ΔH°rxn = –3857 kJ/mol Given that ΔH°f[CO2(g)] = –393.5 kJ/mol and ΔH°f[H2O(l)] = –285.8 kJ/mol, calculate the enthalpy of formation of glycine.
Answer:
ΔH°f C₂H₅O₂N(s) = -537.2kJ
Explanation:
Based on the reaction:
4 C₂H₅O₂N(s) + 9O₂(g) → 8CO₂(g) + 10H₂O(l) + 2N₂(g)
ΔHrxn = ΔH°f products - ΔH°f reactants.
As:
ΔH°fO₂(g) = 0
ΔH°fCO₂(g) = -393.5kJ/mol
ΔH°fH₂O(l) = -285.8kJ/mol
ΔH°fN₂(g) = 0
The ΔHrxn is:
ΔHrxn = (8×-393.5kJ/mol + 10×-285.8kJ/mol) - (4×ΔH°fC₂H₅O₂N(s)) = -3857kJ/mol
-6006kJ/mol - (4×ΔH°fC₂H₅O₂N(s)) = -3857kJ/mol
-4×ΔH°fC₂H₅O₂N(s) = 2149kJ/mol
ΔH°fC₂H₅O₂N(s) = 2149kJ/mol / -4
ΔH°f C₂H₅O₂N(s) = -537.2kJThe boiling point of ethanol is 78.40°C. A student conducts an
experiment and finds a boiling point of 75.70°C. How far off
from the accepted value was the student's result?
Error = °C
Answer:
2.7 °C
Explanation:
78.4-75.7=2.7
The student's result is 2.7° C less than the expected result.
We have a student conducting an experiment to find the boiling point of ethanol.
We have to determine how far off from the accepted value is the student's result.
What is Measurement error ?Measurement Error (also called Observational Error) is the difference between a measured quantity and its true value.
According to the question, we have -
True value of the boiling point of ethanol [T] = 78.40°C.
Measured value of the boiling point of ethanol [M] = 75.70°C.
The Error (E) in the measurement will be -
E = T - M
E = 78.40° - 75.70° = 2.7° C
Hence, the student's result is 2.7° C less than the expected result.
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Two samples of the same rainwater are tested using two indicators at an environrnental lab. The first indicator, Methyl Orange, reveals a distinct yellow color when added to the sample. The second indicator, Litmus, turns red when placed in contact with the water sample.
Required:
a. Identify a possible pH value for the rainwater.
b. Explain, in terms of hydronium ions and hydroxide ion concentrations, the pH value of the rainwater.
Answer:
A. The pH value of rainwater is acidic about 4.4
B. The molar concentrations of the Hydronium ions are more than that of the hydroxide ions. That is why the rainwater is acidic with a pH of less than 7
Explanation:
A. Methyl orange is an acid indicator that is used to detect acidic solutions which have pH values that fall within the range of about 4.4 to 7. The distinct yellow colour change that was shown by the methyl orange as it was added to the water shows that the pH value is acidic, with a value above 4.4. (it has to be like this before methyl orange changes to yellow colour)
B. The Hydronium ( H30+) ion concentrations and the hydroxide (OH-) ion concentrations are used to measure the pH values of substances.
We can tell that the Hydronium ( H30+) ion concentrations are more than the hydroxide (OH-) ion concentrations in the sample of rainwater tested. This can be detected from the colour change that both the methyl orange and the litmus paper gave. The indicators showed that the rainwater solution was indeed acidic. Hence, the pH value will be less than 7, but greater than 4.4.
